This invention relates to the permanent anchoring of dental attachments to the jawbone of a patient by use of a metallic implant.
The use of implants in the bone tissue of the mandibular ridge for anchoring of dental attachments such as artificial teeth and crowns, are well known. In some prior art arrangements the implant is of an elastically resilient type occupying the socket from which the root portion of a natural tooth was extracted. Other prior art implants feature relatively thin, blade elements embedded in the bone tissue without regard to any socket remaining after extraction of the natural tooth. A major problem arising with such dental implants resides in the unfavorable reaction of bone tissue to forces transmitted through the dental implants. Occlusal forces applied either obliquely or producing a horizontal component when acting upon cuspal inclinations, cause mobility and/or injury because of the ill effects of the leverage associated with such dental implants. Very often, such prior dental implants will loosen or cause periodontal destruction to a greater extent than that occasioned with natural teeth in a weakened environment.
It is therefore an important object of the present invention to provide a dental implant for anchoring dental attachments in such a manner as to improve reaction of bone tissue to transmitted forces by a beneficial modification in the leverage arrangement of the dental implant as compared to that of the natural tooth and the leverage arrangements associated with prior dental implants.
In accordance with the present invention, a dental implant is arranged to stabilize itself once embedded within the bone tissue in order to better resist those occlusal forces tending to rotate the tooth about its center of rotation causing periodontal destruction and loosening of the implant. This is effected by a special design of the implant body which raises the center of rotation from the usual location associated with the root portion of a normal tooth and balances moments tending to produce implant rotation. As in the case of the Linkow and Edelman patents aforementioned, the implant body of the present invention includes a substantially thin, planar base or blade embedded within the bone tissue of the mandibular ridge. Unlike, the implant bodies disclosed in the foregoing prior art patents, however, the base of the dental implant according to the present invention is provided with a rounded bottom edge in order to produce a stabilizing effect on the implant base by preventing buccal-lingual movement. The other edge of the implant base is spaced from the crest of the ridge by a distance equal to a rectangular shoulder portion of a shank projecting from this edge of the base toward a support abutment exposed above the gum line and on which an attachment crown in secured. The shank projecting from the base is provided with a necked down portion confined to the gingival and terminating in an enlarged gingival collar from which the support abutment projects. A peripheral shoulder surface on the gingival collar is exposed in surrounding relation to the support abutment in order to receive the connecting crown of a fixed bridge, for example. The necked down portion of the shank provides a tight gingival attachment. The base extends laterally in a mesial-distal direction from the shank with the side surfaces thereof recessed and provided with at least one substantially rectangular opening through which bone tissue may grow after the implant body has been inserted. A stabilizer formation is connected to the edge portion of the implant base from which the shank projects and extends in substantially parallel spaced relation to the relatively planar base in overlying alignment with the rectangular opening. The edge portion of the implant base from which the shank projects is provided with a flat edge surface within which a groove and notch may be formed for an implant inserting instrument.
The stabilizer formation, the rounded bottom edge on the implant base and the recessed intermediate portions of the base along its length in the mesial-distal direction, prevents loosening of the implant once properly inserted with the proper prosthetic appliance thereon. The foregoing arrangement is such that occlusal forces applied to the dental attachment will result in an equilibrium of moments and a favorable transmission of tensile forces so that the bone is stimulated and deposited through the rectangular openings in the implant base by the adjacent trabeculated bone. The implant body is thus retained in place with a minimum of fibrous connective tissue separating the metal portion of the implant base from the trabeculated bone.
These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.